The objective of this research is to determine the major phosphorylation sites in HCV NS5A. Samples related to this project have been submitted to the mass spectrometry facility on two occasions in an attempt to I) identify phosphorylation sites from the mass of purified, phosphorylated NS5A tryptic peptides based on the known amino-acid sequence of HCV NS5A and predicted trypsin cleavage sites or ii) verify the purity and mass of a synthetic peptide based on the major phosphorylation site of HCV-H NS5A.